The body is high quality steel casting, with a high
structural strength and good stability; the jaws are hardened treated chromium
steel with very high hardness and toughness, the jaws including Shrinker and
stretcher, the Shrinker forms outside radius curves and the stretcher forms
inside radius curves. Compound curves can be made by working the piece on
alternating sides, when both Shrinker and stretcher, taking care to match work
on both sides,